1. Field of the Invention
The present invention relates to a terminal fitting to be connected to flat cables such as FPC (flexible printed circuit) or FFC (flexible flat cable) for surface mounting system.
2, Description of the Related Art
Various electric components are installed on a vehicle. A wire harness is arranged in the vehicle for supplying power or transmitting control signals and the like. The wire harness includes a plurality of wires and connectors. The wire is so-called coated electric wire having a conductive core wire and an insulator coating the core wire.
The connector includes a pair of insulating connector housings engaged with each other and conductive terminal fittings received in the connector housings. The terminal fitting includes: an electrical connection portion attached to an end of the wire for electrically connecting the core wire; and an electrical contact portion for contacting a mating terminal fitting. The connector housings connected to each other allow the wire harness to transmit the signals and the like to the electric components.
Nowadays, as the number of the electric components of the vehicle increases, the number of the wire harnesses increases. Therefore, FPC, FFC and the like (hereafter referred to as “cables for surface mounting”) is heavily used.
A terminal fitting 101 in FIG. 9 is well known as a terminal fitting for use in the cables for surface mounting. The terminal fitting 101 includes: an electrical contact portion 111 for being connected to a mating terminal, and a wire connection portion 112 having a bottom wall 113 extended from the electrical contact portion 111 and crimping blades 114 vertically extended from both edges of the bottom wall 113.
The terminal fitting 101 is formed by, for example, bending a metal sheet. The crimping blades 114 are to be bent inward in order to crimp and hold the cables for surface mounting and stick into conductors of the cable. A gap W1 between the crimping blades 114 is narrower than that of the cable for surface mounting. The wire harness is formed by the cables for surface mounting connected to the terminal fittings 101, terminals of which are received in a connector housing.
Incidentally, as the components in a vehicle are mounted in higher density, the width of the cables for surface mounting becomes narrower. Accordingly, the gap W1 between the crimping blades 114 of the terminal fitting 101 reaches the minimum thereof. The minimum width of the gap W1 is at least caused by an existence of a minimum curvature radius between the bottom wall 113 and the crimping blades 114 limited by metalworking technique. Therefore, there is a problem that small sizing of the widths of the cables for surface mounting is limited by the manufacturable size of the terminal fitting 101.
For solving the problem, as shown in FIGS. 10 to 13, some terminal fittings having structures adapted for the cables for surface mounting having narrower widths are already proposed.
A terminal fitting 201 shown in FIGS. 10 and 11 (disclosed by Japanese Published Patent Application No. 2003-317829) includes a rectangular parallelepiped electrical contact portion 211 and a bottom wall 213 for overlapping with a FFC 103. The FFC 103 includes a flat conductor 131 covered by an insulator 132. When the bottom wall 213 overlaps with the FFC 103, the terminal fitting 201 is connected to the FFC 103 through the conductor 131 exposed from sections around a slit A of the FFC 103 and an arched portion of the bottom wall 213.
However, because the FFC 103 and the terminal fitting 201 are not fixed to each other mechanically firmly, there is a problem that connection reliability of the terminal fitting 201 is not high. Further, there is another problem that the exposed conductor 131 of the FFC 103 may be oxidized by the air, and electric resistivity may be increased.
As shown in FIG. 12, a terminal fitting 301 (disclosed by Japanese Published Patent Application No. 2002-305042) includes a rectangular parallelepiped electrical contact portion 311 and a wire connection portion 312 having a bottom wall 313 extended from the electrical contact portion 311 and crimping blades 314 vertically extended from one of edges of the bottom wall 313. Because the crimping blades 314 are disposed solely at the one edge of the bottom wall 313, the crimping blades 314 are allowed to stick into the cables for surface mounting having narrower conductor.
However, because the crimping blades 314 are disposed at the one edge of the bottom wall 313, the terminal fitting 301 is easily inclined. Further, when the crimping blades 314 stick into the cables for surface mounting, the cables for surface mounting are easily moved relative to the terminal fitting 301. Therefore, there is a problem that the connection reliability of the terminal fitting 301 is not high.
As shown in FIG. 13, a terminal fitting 401 (disclosed by Japanese Published Patent Application No. 2002-305050) includes a rectangular parallelepiped electrical contact portion 411 and a wire connection portion 412 having a bottom wall 413 extended from the electrical contact portion 411 and crimping blades 414 vertically extended along the transversal center of the bottom wall 313. The crimping blades 414 are formed by bending twice extended portions of the metal plate transversely from the bottom wall 413.
However, because the crimping blades 414 are vertically extended by bending twice extended portions of the metal plate, there is a problem that mechanical strength of the crimping blades 414, productivity and mechanical accuracy of the terminal fitting 401 are not high.
Accordingly, an object of the present invention is to provide a terminal fitting for connecting to cables for surface mounting having narrow conductors with high connection reliability and high productivity.